UP Board Class 9 Science Chapter 11 Sound Multiple Choice Questions

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Sound Multiple Choice Questions

Question 1. Sound waves transfer

  1. Only energy not momentum
  2. Energy
  3. Momentum
  4. Both (2) and (3)

Answer: 4. Both (2) and (3)

Sound waves transfer both energy and momentum by the process of compression and rarefaction.

Question 2. Which of the following does not produce sound waves?

  1. Drum
  2. Birds
  3. TV
  4. Microwave oven

Answer: 4. Microwave oven

A microwave oven is used to produce electromagnetic waves.

Question 3. A tuning fork produces sound waves because it creates

  1. Heat
  2. Light
  3. Vibration
  4. None of these

Answer: 3. Vibration

If the tuning fork is vibrating, it produces sound.

Question 4. Which of the following does not create a transverse wave?

  1. Slinky
  2. Heater
  3. Rope
  4. None of these

Answer: 1. Slinky

In a slinky, the individual particles simply oscillate back and forth about their position of rest.

Question 5. The speed of sound is maximum in

  1. Air
  2. Vacuum
  3. Liquid
  4. Metal

Answer: 4. Metal

The speed of sound is maximum in solids like metals.

UP Board Class 9 Science Chapter 11 Sound Multiple Choice Questions

Question 6. What is the range of audio waves?

  1. 20 kHz to 200 kHz
  2. 20 Hz to 20 kHz
  3. 20 Hz to 20 MHz
  4. 20 Hz to 20 MHz

Answer: 2. 20 Hz to 20 kHz

The range of sound waves is 20 Hz to 20 kHz.

Question 7. The frequency of a source of sound is 200 Hz. How many times does it vibrate in 2 min?

  1. 2400
  2. 24000
  3. 24500
  4. 2450

Answer: 2. 24000

Given, frequency = 200 Hz

Number of oscillations in Is = 200

Number of oscillations in 2 min or 120 s

= 200×120 = 24000

Question 8. Which wave property determines the loudness of sound?

  1. Frequency
  2. Pitch
  3. Speed
  4. Amplitude

Answer: 4. Amplitude

The loudness of a sound wave is determined by its amplitude.

Question 9. Echo is caused by the phenomenon of

  1. Reflection
  2. Rarefaction
  3. Refraction
  4. Reverberation

Answer: 1. Reflection

An echo is the reflected sound wave.

Question 10. A man’s voice and a woman’s voice differ by its

  1. Loudness
  2. Pitch
  3. Intensity
  4. Amplitude

Answer: 2. Pitch

Pitch is the characteristic of sound by which we can distinguish between different sounds of the same loudness.

Question 11. In older age, it is difficult to recognise

  1. lower frequency
  2. medium frequency
  3. higher frequency
  4. ultrasonic sound

Answer: 3. higher frequency

Higher frequencies require, high sensitivity, so for older age, it is difficult to recognise them.

Question 12. A stone is dropped from the top of Qutub Minar 73 m high into a pond of water at the base of the Qutub Minar. When is the splash heard at the top?[Take, g=10 ms-2 and speed of sound = 340 ms-1]

  1. 1.82 s
  2. 2.83 s
  3. 3.82 s
  4. 4.32 s

Answer: 3. 3.82 s

From the second equation of motion,

h =\(u t+\frac{1}{2} g t^2\)

73 =0 \(\times t+\frac{1}{2} \times 10 \times t^2\) [u=0]

⇒ \(5 t^2\) =73

∴ \(t^2 =\frac{73}{5}=14.6 \Rightarrow t=\sqrt{14.6}=3.82 \mathrm{~s}\)

Question 13. A sound wave is generated by a tuning fork. It is measured that the sound wave has a speed of 500 ms-1. If its wavelength is 1 cm, will it be audible?

  1. Audible
  2. Non-audible
  3. Both
  4. None of these

Answer: 2. Non-audible

Given, speed, \(\nu=500 \mathrm{~ms}^{-1}\)

Wavelength, \(\lambda=1 \mathrm{~cm}=10^{-2} \mathrm{~m}\)

Frequency, v=\(\frac{v}{\lambda}=\frac{500}{10^{-2}}=50000 \mathrm{~Hz}\)

This frequency is greater than 20000 Hz. So, it is not audible.

Question 14. A guitar of frequency 360 Hz makes 120 vibrations. If the velocity of sound in air is 330 m/s, then how much distance is travelled by the sound in air?

  1. 90 m
  2. 100 m
  3. 110 m
  4. 140 m

Answer: 3. 110 m

Given, v=360 Hz

Velocity, v=330 \(\mathrm{~m} / \mathrm{s}\)

As, \(\lambda=\frac{v}{v}=\frac{330}{360}=\frac{33}{36} \mathrm{~m}\)

Distance travelled by the sound wave in 120 vibrations =120 \(\times \frac{33}{36}=110 \mathrm{~m}\)

Question 15. What is the SI unit of loudness?

  1. Dioptre
  2. Metre
  3. Weber
  4. Decibel

Answer: 4. Decibel

The SI unit of loudness is decibel (dB).

Question 16. A man beating a drum in front of a cliff hears the echo after 4s. What is the distance of man from the cliff, if the velocity of sound in air is 330 m/s?

  1. 660 m
  2. 500 m
  3. 1000 m
  4. 0.3 km

Answer: 1. 660 m

As we know that, distance, s = speed x time = 330 x 4 =1320 m

As in 4s, sound has to travel twice the distance between man and the cliff.

So, the distance between man and cliff is \(\frac{s}{2}=\frac{1320}{2}=660 \mathrm{~m}\)

Question 17. At which frequency, a guitar produces 1000 sound waves per second?

  1. 1 kHz
  2. 500 Hz
  3. 700 Hz
  4. 1200 Hz

Answer: 1. 1 kHz

The frequency of sound valves is called the number of waves, produced in 1s.

So the frequency of this sound wave is 1000 Hz or 1 kHz.

Question 18. A light string is suspended from a book. Which is attached to a 1 kg weight at its lower end. If the string is pulled right and then released. The disturbance produced in the spring is

  1. Pulse
  2. Longitudinal wave
  3. Transverse wave
  4. None of these

Answer: 3. Transverse wave

Here suing is vibrating which shows crest and trough which are the signs of a transverse wave.

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